consists of a lattice of positive ions surrounded by a ‘sea’ of mobile delocalised valence electrons. • Metallic bonding is the electrostatic attraction between the delocalised electrons and the positive ions in the metallic lattice. Properties of metals: Property Explanation Relatively high density The particles are very close together. This is because of high electrostatic forces between the sea of valence electrons and the positively charged nucleus. Malleability and Ductility Because metallic bonding
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bond when atoms share pairs of electron to become stable. For covalent bonding‚ two or more elements must have shared electrons. Atoms become stable by filling up their outermost shell with shared electrons. An atom can only have 8 electrons and that rule came from the Octet
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protons‚ electrons‚ and neutrons. Protons carry a positive electrical charge‚ electrons carry a negative electrical charge‚ and neutrons carry no electrical charge at all. The protons and neutrons come together in the central part of the atom‚ called the nucleus‚ and the electrons ’orbit’ the nucleus in the electron cloud. An element is a substance that is made entirely from one type of atom. For example‚ the element hydrogen is made from atoms containing a single proton and a single electron. If you
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electrolyte‚ an anode and a cathode partitioned by a proton exchange membrane as shown in figure1 (Du‚ Li and Gu 2007). At the anode‚ microbial respiration oxidizes available substrates to carbon dioxide results in liberation of electrons and protons. These electrons are transported out of the cell to the electrolytes via electrochemically active carriers‚ also known as
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charged protons and neutrally charged neutrons an electron cloud of negatively charged electrons An atom is a neutral particle containing an equal number of protons and electrons Molecule: a group of two or more atoms held together by chemical bonds Ion: an atom that has a positive or negative charge cation: lost electrons; takes on a positive charge (more protons than electrons) anion: gained electrons; takes on a negative charge (more electrons than protons) Chemical Bonds: form between atoms
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many valence (outer shell) electrons are posessed by each atom in the molecule. 2. If there is more than one atom type in the molecule‚ put the most metallic or least electronegative atom in the center. Recall that electronegativity decreases as atom moves further away from fluorine on the periodic chart. Arrangement of atoms in CO2: 3. Arrange the electrons so that each atom contributes one electron to a single bond between each atom. 4. Count the electrons around each atom: are the
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Chapter 7 same number of valence electrons=behave similarly(chemical properties) ▪ neon gases (neon‚ argon) unreactive in chemical reactions(stable) ▪ Gilbert Lewis-octet rule(atoms tend to achieve electron configuration of gas) ▪ atoms of metallic atoms lose electrons‚ atoms of nonmetal atoms lose or share electrons with another nonmetal elements to achieve a complete octet ▪ to achieve octet‚ change electrons to ge ns2 np6 configuration ▪ remove electrons=ionization ▪ metals in group
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are electronic neutral. Covalent bonds are bonds that don’t give or take any electrons. In stead they share the elctrons 50) Which of these compounds contain elements that do not follow the octet rule? Explain. a) NF3: 5 + (7*3) = 26 b) PCl2F3: 5 + (7*2) + (7*3) = 40 c) SF4: 6 + (7 *4) = 24 d) SCl2: 6 + (7*2) = 20 The answer is “d” because it does not have eight valence electrons. 64) Explain why each electron structure is incorrect. Replace each structure with one that is more acceptable
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some other molecules Influence of the nature of electron pairs on bond angles in molecules of methane‚ ammonia and water Shapes of some polyatomic ions Shapes of molecules with multiple bonds Molecular crystals of buckminsterfullerene (C60) 23.1 – 23.7 Summary 1 Examples of covalent molecules with non-octet structures are as follows: Molecule Electron diagram F BF3 B F F SF4 F Molecule Electron diagram F S F F Cl PCl5 Cl Cl P Cl Cl SF6 F F
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the ability to "remember" the magnetic fields they have been subjected to. An atom consists of a number of negatively charged electrons‚ orbiting around a positively charged nucleus. These electrons also possess a quantity known as spin‚ which is roughly analogous to a spinning top. The combination of orbital and spin motions is called the angular momentum of the electron. Angular momentum is perhaps most easily understood in the case of the Earth: The earth spins about a central axis‚ which means
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